The Lib Dems' Chris Huhne, left, led the attack on David Cameron and the Tories. Photograph: Reuters

The deepening loss of personal trust at the top of the coalition government engendered by the bitter AV referendum campaign was exposed when David Cameron was accused of a systematic and shortsighted attempt to trash Nick Clegg's leadership.

The attack by the energy secretary, Chris Huhne, in the final week of the campaign further exposes the deep anger among Liberal Democrats that Cameron is using the referendum to shore up his position within the Conservative party at Clegg's expense.

Huhne expressed anger over widely circulated no campaign leaflets that focus on Clegg's alleged broken pledges. He told the Guardian: "David Cameron has had the power to stop these no campaign leaflets saying Nick Clegg has broken promises and told lies. He has done nothing about it.

"To attack your political colleagues in a coalition and Nick Clegg in particular for accepting the compromises necessary to allow the Conservatives to implement some of its policies is absurdly short-sighted and outrageous.

"Our two parties came together in the national interest in order to deal with our country's economic problems. The Conservative party is now completely trashing us and Nick Clegg's leadership for doing something they asked us to do in the national interest."

Huhne's remarks constitute the most personal attack on Cameron mounted by a Lib Dem during the referendum campaign. Huhne, who has taken more risks than any other Lib Dem cabinet member to take the fight to the Conservatives during the campaign, said the no camp was run and wholly funded by the Conservative party, and if Cameron wanted to stop the leaflets he could have done so. Cameron insisted he was only responsible for the Conservative no campaign, and not the wider all-party campaign.

The latest row follows a Sunday Times/YouGov poll that showed some tightening in the race, with the no lead narrowing from 18 points to a still emphatic 10. There is some sign that Labour voters now believe it is in their better long-term interest to damage Cameron by voting yes than it is to vote no and punish Clegg.

But the yes campaign is still only leading in Scotland, suggesting that despite the fluctuating polls it may have an insurmountable job to turn a tentative shift into a decisive victory by Thursday.

Both Clegg and Cameron said the coalition would survive Thursday's results, which could also see the loss of 600 Conservative councillors and as many as 400 Liberal Democrats.

Speaking on the BBC's Andrew Marr Show, Cameron said he would not be giving his coalition partners any consolation prizes if they were defeated in the referendum. "I don't believe that a successful coalition is based around trying to endlessly sort of trade off each other's policies."

But he signalled he wanted to revise his plans to introduce GP-led commissioning in the NHS so that the reform did not exclude hospital doctors.

Meanwhile, Clegg accused the no campaign of trying to sow confusion over AV. But he acknowledged that "at a time of some anxiety … it's sometimes quite a challenge to persuade people that we need to change things, move with the times". He said the campaign had shown "this coalition government is composed of different parties with different values and different identities; maybe in the long run that's not a bad thing".

The Labour leader, Ed Miliband, also waded into the dispute yesterday, saying: "I have always thought that this is likely to be a five-year government. I think it is less likely after the rows of the last month."

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